Diblock Copolymer Film Orientation via Graphoepitaxy and Annealing
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Solution Overview
Problem
Conventional methods struggle to fabricate ordered arrays of nanoscale linear structures outside of trenches over large areas, as self-assembling diblock copolymer films on flat substrates typically form disordered patterns, limiting the scalability and manufacturability of nanoscale devices.
Innovation Solution
The use of graphoepitaxy techniques with trenches to induce orientation and registration of self-assembling diblock copolymer films, where a base layer with ordered structures within trenches is used to template a lamellar-phase block copolymer film, allowing for perpendicular orientation and registration of lamellar domains, and subsequent localized annealing to extend the ordered pattern beyond trench boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If self-assembling diblock copolymer films are prepared on a flat substrate and annealed, then the polymer blocks can microphase separate and self-assemble into periodic structures, but the domains will form disordered fingerprint-like structures without preferential orientation despite extensive annealing
Solution Approach 1:
The substrate surface is pre-modified with self-assembled monolayers (SAMs) that have different surface energies before the copolymer film is deposited. This preliminary surface preparation creates preferential wetting sites that guide the orientation of copolymer domains during self-assembly, eliminating the need for extensive annealing time to achieve ordered structures.
Solution Approach 2:
The surface energy parameters of the substrate are modified by introducing SAMs with specific chemical compositions and orientations. This changes the interfacial interaction parameters between the substrate and copolymer blocks, enabling controlled orientation of domains without requiring long annealing periods.
2Manufacturing precision
If graphoepitaxy techniques using trenches are used to orient and order copolymer domains, then registered and ordered arrays can be produced within trenches, but the ordered array cannot be extended beyond the confines of the trenches over large areas in a manufacturable process
Solution Approach 1:
The SAM-modified substrate provides a universal orientation template that works both within trench regions and in extrinsic areas. The same surface energy gradients and preferential wetting mechanisms that order domains within trenches also guide domain orientation in surrounding areas, enabling large-scale ordered pattern formation without requiring physical trench boundaries.
Solution Approach 2:
The orientation-controlling function is extracted from the physical trench structure and transferred to the chemical surface modification (SAMs). This allows the orientation mechanism to operate independently of trench boundaries, enabling ordered patterns to extend beyond trench confines into large areas.
3Ease of manufacture
If conventional optical lithographic processing methods are used, then the process is cost-effective, but structures and features much below a 100 nm level cannot be fabricated
Solution Approach 1:
The diblock copolymer system performs self-assembly and self-ordering when deposited on the SAM-modified substrate. The copolymer blocks automatically microphase separate into ordered periodic structures with dimensions below 100 nm, eliminating the need for expensive high-resolution lithography tools while achieving the required structural precision.
4Manufacturing precision
If electron beam lithography or EUV photolithography are used to achieve comparable resolution, then nanoscale structures can be fabricated, but the cost is far greater than self-assembling copolymer methods
Solution Approach 1:
The SAM-modified substrate creates a template pattern that is copied by the self-assembling copolymer domains. This template-directed self-assembly produces nanoscale features with high precision without requiring expensive electron beam or EUV lithography equipment, achieving comparable resolution at much lower cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the fabrication of ordered nanoscale linear arrays over large areas, overcoming the limitations of conventional techniques by achieving registered and ordered patterns beyond trench confines, suitable for nanoscale device fabrication with reduced costs compared to other high-resolution methods like electron beam or EUV photolithography.
Implementation Method 1
Diblock copolymer films spontaneously assemble into periodic structures by microphase separation of the constituent polymer blocks after annealing, for example, by thermal annealing above the glass transition temperature of the polymer
Implementation Method 2
thermal annealing above the glass transition temperature of the polymer
Implementation Method 3
Registered and ordered arrays of cylinders have been produced within trenches by use of directed thermal energy to anneal a copolymer film
Data Source
AI summary
Methods for fabricating sub-lithographic, nanoscale linear microchannel arrays over surfaces without defined features utilizing self-assembling block copolymers, and films and devices formed from these methods are provided. Embodiments of the methods use a multi-layer induced ordering approach to align lamellar films to an underlying base film within trenches, and localized heating to anneal the lamellar-phase block copolymer film overlying the trenches and outwardly over the remaining surface.